Dentin is the substance between enamel or cementum and the pulp chamber. It is secreted by the odontoblasts of the dental pulp. The formation of dentin is known as dentinogenesis. The porous, yellow-hued material is made up of 70% inorganic materials, 20% organic materials, and 10% water by weight.
Medical Definition of metaplasia. 1  1: transformation of one tissue into another metaplasia of cartilage into bone. 2  2: abnormal replacement of cells of one type by cells of another.
Compare anaplasia. metastasize, v. , metastatic adj. Plural, metastases Oncology The distal spread of a malignancy, either by penetration of a blood or lymphatic vessel or by spread along a serosal membrane with later development into a 2 nd focus of malignancy.